U.S. Pat. No. 6,395,231 describes a device for storing and providing objects having standardized dimensions. The applicant produces and sells such a device.
Since standardized well microplates that comply with U.S. standard ANSI/SBS 2-2004 “Footprint Dimensions” for microplates are employed to load and unload objects having standardized dimensions such as those used in many technical laboratory applications in the realm of research in molecular biology, biochemistry and molecular genetics as well as in medicine, biotechnology and diagnostics, conventional devices do not differ in terms of the shape and size of the footprint of the stackers, which are also referred to as racks or magazines. These standardized well microplates are plates having a standardized footprint size of 127.76 mm×85.48 mm. However, the device can also hold other standardized objects such as, for instance, containers for pipette tips, plates for storing specimens or else packaging units, for example, a well microplate with a lid, which is why the term “object” will be generally employed below. In order to accommodate as many objects as possible in the device, the objects are stacked and stored in a stacker, and as many such stackers as possible are arranged in a storage space in the device.
The stackers can contain storage compartments into each of which an object can be placed, so that these objects can be loaded or unloaded in any desired sequence using an unloading device (random access).
The objects can also be situated directly one above the other in a stacker, whereby the lowermost object rests on adjustable placement and separation elements (“separation elements” below) that are moved in order to transfer the lowermost object into an unloading device.
Two principles are typically employed for loading and unloading the stackers with objects. According to the so-called “first in, first out” (FIFO) principle, the first object to be loaded into a stacker is also the first to be unloaded again. A device that operates according to the FIFO principle is, for example, the Q-Stacker (model QR-210) made by PEAK ROBOTICS, INC.
The second principle is referred to as “last in, first out” (LIFO). In this case, the last objects to be loaded into a stacker are the first ones to be unloaded again. An example of this is the Tomtec Quadra 3® (Tomtec, Hamden, Conn., U.S.A.).
FIGS. 1a to 1g show an example of the procedure for loading an object 5 that is to be loaded into a stacker 3 according to the device described in U.S. Pat. No. 6,395,231.
The object 5 to be loaded is placed by means of an unloading device 12.1 located in an initial position beneath a bottom surface 3.2 of the stacker 3. An object 5 that is already present in the stacker 3 rests on a closed separation device 8 that is configured so that it can extend in a controlled manner and reversibly into the free cross section of the stacker 3. The object 5 present in the stacker 3 is held by the separation device 8 (FIG. 1a). The unloading device 12.1 brings the object 5 to be loaded into the stacker 3 from below in that the unloading device 12.1 is moved in the direction of the bottom surface 3.2 by means of a drive 12.2 of the unloading device (FIG. 1b). When the object 5 that is present is raised, latches 8.1 that can extend in a controlled manner and reversibly into the free cross section of the stacker 3 are magnetically retracted from the free cross section of the stacker 3, and the separation device 8 is opened (FIG. 1c). In this process, the two objects 5 come into contact with each other via a contact surface. The object 5 to be loaded is moved entirely into the stacker 3 by means of the unloading device 12.1. The object 5 that is already present in the stacker 3 is lifted by the object 5 that is to be loaded and by the unloading device 12.1, and then pushed further along the stacker 3 (FIG. 1d). The separation device 8 is then closed, as a result of which the latches 8.1 extend into the free cross section of the stacker 3 and underneath the two objects 5 (FIG. 1e). The unloading device 12.1 is moved downwards, as a result of which the two objects 5 are lowered in the stacker 3 until they come to rest on the latches 8.1 and are held by them (FIG. 1f). The unloading device 12.1 is moved back to its initial position, while the two objects 5 remain in the stacker 3 (FIG. 1g). An object 5 can be unloaded from the stacker 3 analogously.
According to U.S. Pat. No. 6,129,428 A, the stackers are arranged like a carrousel on a turntable. The individual stackers are oriented radially towards the outside. In order for an object to be unloaded from a storage compartment of a stacker, there is an unloading device that is configured here as a stationary lifting mechanism with a conveying platform that can be swiveled horizontally. Here, the appertaining stacker is rotated by the turntable towards the lifting mechanism to a transfer position, the conveying platform is moved to the height of the selected storage compartment and swiveled towards the storage compartment so that the object can be loaded or unloaded
A drawback of the described carrousel-like arrangement of the stackers with respect to each other is that the ratio of the number of stackers to the required size of the turntable (below referred to as the density) worsens as the number of stackers increases.
A storage unit according to U.S. Pat. No. 7,214,022 B2 and U.S. Pat. Appl. No. 2004/0004415 A1 promises a higher density in that two parallel rows of storage slots are arranged on shelves on both sides of a passage in which a pick-up unit can be moved back and forth between transfer positions so that an object can be loaded or unloaded by means of the unloading device.
U.S. Pat. Appl. No. 2009/0026905 A1 and U.S. Pat. Appl. No. 2008/0272674 A1 describe a storage unit, especially for a climate controlled cabinet, in which several rows of parallel storage slots are arranged in a shelf, and the unloading device is configured in such a way that it can pick up a number of objects that matches the number of rows, so that in one transfer position, all of the objects located one behind the other are unloaded. A separation device then removes an object from the unloading device and the remaining objects are deposited once again. Such an approach further increases the density.
The RapidStak® system (Thermo Fischer) (http:www.thermo.com/eThermo/CMA/PDFs/Product/productPDF—1133.pdf; downloaded on Jun. 24, 2010) describes a device for storing and providing objects having standardized dimensions, wherein the objects are unloaded and dispensed from the stackers by means of an unloading and providing device at transfer positions that are each always associated with one stacker. The unloading and providing device can be moved in an x-y plane and can be brought to the transfer position of each stacker. In this context, the unloading and providing device is moved by means of a first module in the direction of the x-axis and of a z-axis that is perpendicular to the x-y plane, while the movement in the direction of the y-axis is effectuated by a second module that differs from the first module. With the approach according to The RapidStak® system, only the stackers that are arranged directly on the appertaining side can be loaded or unloaded from one side of the device. Consequently, in order for objects to be loaded in to or unloaded from the individual stackers, there has to be a great deal of access space at the side of and above The RapidStak® system. This, however, makes it very difficult to install and load the system in constricted spaces such as, for example, in a chamber.
The applicant designs, produces and sells a device that stores and dispenses objects having standardized dimensions and that serves as an accessory for pipetting systems such as, for instance, CyBi®-Well and JOBI-Well (FIG. 2).
The device described in U.S. Pat. No. 6,395,231 comprises a storage unit 1 having a carrier plate 2 and two vertical stackers 3 that are each arranged with their bottom surface 3.2 on the top of the carrier plate 2. A transfer position 6 (indicated by arrows) at an opening 7 is associated with each stacker 3, whereby the transfer positions 6 are oriented parallel to each other and facing in the same direction. Moreover, there is a substructure 11 on which the carrier plate 2 rests. There is also an unloading and providing device 12. One free wall 3.11 of each stacker 3 has a door 3.5 through which the stacker 3 can easily be loaded when said door is open.
Conventional devices have one stacker per transfer position, each of which has to be approached by an unloading device, as a result of which the cycle times that can be achieved are limited. Moreover, due to the different lengths of the movement distances that the unloading device has to travel to the various transfer positions, the cycle times also differ, which is disadvantageous from the standpoint of automation.